In-line particle detection for immersion lithography

Abstract

An immersion lithography system, comprising a lens unit configured to project a pattern from an end thereof and onto a wafer, a hood unit configured to confine an immersion fluid to a region of the wafer surrounding the end of the lens unit, a wafer stage configured to position the wafer proximate the end of the lens unit, and at least one of an image capturing apparatus and a scattering light detection apparatus, wherein the image capturing apparatus is coupled to the wafer stage and is configured to capture an image of a surface of the hood unit proximate the wafer stage, and wherein the scattering light detection apparatus is proximate the end of the lens unit and the hood unit and is configured to detect particles on a surface of the wafer stage.

Dependencies are inferred from the claim text.